1. Field of the Invention
The present invention relates to an interconnect device for detecting whether an vehicle on-board diagnostics (OBD) data port includes circuitry or other means that prevents back feeding of power through the OBD data port.
2. Description of the Prior Art
An on-board diagnostics (OBD) data port is mandated by the US government to be supplied on every car sold in the US since 1996. Other countries have similar standards. For example Europe has EOBD and EOBD2 standards while Japan has a JOBD standard. In the US, the OBD and the OBD data port was originally intended by the Environmental Protection Agency and the California Air Resources Board (CARB) to provide a convenient way to monitor whether the vehicle was running efficiently and cleanly.
The OBD II standard in the US requires that an OBD II data port be located within two feet of the steering wheel. The data port is specified as a 16 pin connector. Since 2008, the signals associated with each of the 16 pins are standardized.
During normal operation, the OBD diagnostic system monitor's various Parameter ID codes (PID). These PID codes relate to the status of the vehicle emissions. These PID codes can be read by connecting a OBD diagnostic tool to the OBD II data port to allow reporting of various of the vehicle systems. In addition to the PID codes mentioned above, various manufacturers include their own PIDs for monitoring other aspects of the vehicle performance that do not directly relate to emissions, for example, the transmission and tire pressure monitoring systems.
The OBD II connectors are also known to be used to preserve certain data that is stored on board the vehicle. This data includes consumer preference data, such as preferred mirror and seat positions, radio stations, GPS preference data and the vehicle clock. Such data is normally lost when the battery is disconnected from the vehicle, creating an inconvenience for the consumer to reprogram the data. In extreme cases, a loss of certain engine data may prevent the vehicle from being restarted.
Various vehicle memory saver devices are known which can supply power to the vehicle on-board computer systems to prevent data loss when the vehicle battery is disconnected. One such device is available from Schumacher Electric Company. The device includes an OBD II connector connected by a cable to a conventional cigarette lighter connector. The OBD II connector is connected to the OBD II data port of the vehicle in which the battery will be disconnected and the cigarette lighter connector is connected to another vehicle or alternate power source.
Unfortunately, some vehicle OBD II data ports include a circuitry or other means in series with the battery connection that prevents back feeding of DC power to the vehicle on-board computer systems. Since there is no convenient way of detecting whether the OBD II includes such circuitry or other means, known devices for back feeding power to the vehicle by way of the OBD II connector are unreliable. If a conventional device for back feeding power to through the OBD II port connector, the power will be blocked by the diode and the data mentioned above will be lost. The user will have no way of knowing this before the battery is disconnected. Thus, there is a need for detecting whether a vehicle OBD II connector includes such circuitry or other means.